Chapter 9: Cellular Respiration

Objectives

The student is responsible for:

1. The definitions of all bold faced words in the chapter

2. Knowing the entire chapter.

The student is not responsible for:

1. Memorizing or drawing the structures of glycolysis or Kreb’s cycle

Principles of Energy Harvest

Fermentation: decomposition of glucose without the use of oxygen

Cellular Respiration: oxygen is a reactant when glucose is broken down

Figure 9.1 Energy flow and chemical recycling in ecosystems

There is an integral relationship between photosynthesis and respiration.

The production of ATP is an exergonic process

Figure 9.x1 ATP

Adenosine Triphosphate

ATP -> ADP + Pi

ADP AMP + Pi

Figure 9.2 A review of how ATP drives cellular workWhy do we care so much about ATP?

Figure 9.3 Methane combustion as an energy-yielding redox reaction

Oxidizing Agent: that substance that is being reduced.

O is “going” from O (no charge) to O2-.

Reducing Agent: that substance that is being oxidized.

C is gaining oxygen.

Figure 9.19 The catabolism of various food molecules

Various foods can be oxidized to produce ATP.

Figure 9.4 NAD+ as an electron shuttle

The molecule that is used to move hydrogen ions throughout the oxidation of food is NAD+. Therefore NAD+ is an oxidizing agent.

NAD+ + H+ NADH

Figure 9.5 An introduction to electron transport chains

Figure 9.6 An overview of cellular respiration (Layer 1)

But if we could get this pyruvate into the mitochondria we could make a whole lot more ATP!!

Figure 9.6 An overview of cellular respiration (Layer 2)

Figure 9.6 An overview of cellular respiration (Layer 3)

Figure 9.7 Substrate-level phosphorylation

What is this substrate-level phosphorylation?

This is when a phosphate group is moved from an organic compound to ADP.

What is oxidative phosphorylation?

When electrons and H+ are used to make ATP.

Figure 9.8 The energy input and output of glycolysis

Couldn’t these NADH’s that are made be used to make ATP?

Figure 9.9 A closer look at glycolysis: energy investment phase (Layer 1)

Figure 9.9 A closer look at glycolysis: energy investment phase (Layer 2)

Figure 9.9 A closer look at glycolysis: energy payoff phase (Layer 3)

Figure 9.9 A closer look at glycolysis: energy payoff phase (Layer 4)

Figure 9.10 Conversion of pyruvate to acetyl CoA, the junction between glycolysis and the Krebs cycle

Could the NADH produced here be used to make ATP?

Figure 9.11 A closer look at the Krebs cycle (Layer 1)

Keep track of the number of carbons!!

Figure 9.11 A closer look at the Krebs cycle (Layer 2)

More NADHs!!!

Figure 9.11 A closer look at the Krebs cycle (Layer 3)

Figure 9.11 A closer look at the Krebs cycle (Layer 4)

Figure 9.12 A summary of the Krebs cycle

Figure 9.13 Free-energy change during electron transport

NADH and FADH2 deliver electrons to different locations in the ETC.

The role of oxygen is to serve as a hydrogen ion acceptor to form water.

Figure 9.14 ATP synthase, a molecular mill

ATP Synthase

Chemiosmosis: the coupling of the movement of H+ through a protein complex (ATP Synthase) making ATP.

Figure 9.15 Chemiosmosis couples the electron transport chain to ATP synthesis

A Proton-Motive Force is produced

Figure 9.16 Review: how each molecule of glucose yields many ATP molecules during cellular respiration

Figure 9.17a Fermentation

Figure 9.17b Fermentation

Figure 9.18 Pyruvate as a key juncture in catabolism

Figure 9.19 The catabolism of various food molecules

Power Bars?

Luna Bars?

Promax?

Goo?

Versatility of Catabolism

Use of Proteins

1. Proteins amino acids and then the amino acids must have their amino groups removed before being used as an energy source. So all the energy bars that have amino acids in them are at least one step closer to being used for energy than a protein.

2. Fats must go through beta oxidation which takes a fat and breaks off 2 carbon fragments from the fatty acids and these 2 carbon fragments enter at acetyl-CoA.

Figure 9.20 The control of cellular respiration 

The Control of Cellular Respiration

1. PFK: allosteric enzyme

a) Receptor sites for ATP, AMP and citrate

b) ATP: inhibitor

c) AMP: stimulator

d) Citrate: inhibitor

The Evolutionary Significance of Glycolysis

Earliest organisms were in an anaerobic environment (3.5 billion yrs ago)

Glycolysis was probably used as an energy making process

Oxygen accumulated about 2.7 billion years ago

Glycolysis is the most widespread pathway amongst organisms suggesting it evolved early on.

Glycolysis requires only the cytoplasm and membrane-bound organelles were not present until eukaryotic cells appeared (2 billion years after prokaryotes)